Indicator definition

Percentage of population connected to primary, secondary and tertiary wastewater treatment plants. The indicator illustrates:

1. changes in wastewater treatment in the regions of Europe since the 1980s;

2. conformity (in terms of providing tertiary treatment) by Member States with the requirement to provide, by 31 December 1998, stringent treatment for agglomerations with population equivalent (p.e.) more than 10 000 that discharge into sensitive areas;

3. levels of urban wastewater treatment in large cities in the EU (agglomerations >150 000 p.e.).

Units

Percentages of population connected to primary, secondary and tertiary wastewater treatment.

Key messages

Wastewater treatment in all parts of Europe has improved during the last 15-20 years. The percentage of the population connected to wastewater treatment in the southern, south-eastern and eastern Europe has increased during last ten years, but is still relative low compared to the central and northern Europe.

Changes in wastewater treatment in regions of Europe between 1990 and 2007

Note:This figure illustrates the percentage population per European region connected to an Urban Wastewater Treatment Plant over the period 1990 to 2007. In addition, a breakdown by treatment type is portrayed.

Data source:

EEA-ETC/WTR (CSI024) based on data reported to OECD/EUROSTAT Joint Questionnaire 2008. Data are available at Eurostat data tables.

Key assessment

The main objective of the Urban Waste Water Treatment (UWWT) Directive and national legislation for non-EU countries is to protect surface waters from the adverse effects of wastewater discharges. This is achieved through the requirement for collection and treatment of wastewater in all settlements (agglomerations) and areas of economic activity with a population equivalent (p.e.) larger than 2000. As a rule, the UWWT Directive provides for biological treatment of waste water (secondary treatment), which would otherwise deplete oxygen levels in receiving waters, threatening aquatic ecosystems. In catchments with particularly sensitive waters (sensitive areas), such as those suffering from eutrophication, more stringent tertiary waste water treatment measures are required, in order to substantially reduce nutrient pollution (nitrogen and phosphorus) from waste water.

Percentage of national population connected to waste water treatment.About 80 % of the population is connected to waste water treatment in Northern and Southern European countries. The connection rate in Central European countries is even higher, at 90 %. On the basis of data reported in 2006-2007, about 65 % of total population is connected to wastewater treatment in the countries of Eastern Europe. Average connection in South-Eastern Europe (Turkey, Bulgaria and Romania) is about 40 % .Percentage of national population connected to tertiary waste water treatmentMore than 70 % of the population in Northern and Central Europe is connected to a wastewater treatment plant that implements tertiary treatment, substantially removing nutrients and organic matter. Wastewater generated by more than 40% of the population in Southern and Eastern Europe receives tertiary treatment. This represents a 20% increase over last five years. In South-Eastern Europe the percentage of population connected to treatment plants with tertiary treatment is low (8,5%), with 21% of the population of the region being connected to secondary treatment.

Timetable for the compliance with the UWWT Directive varies for EU15 and for new EU Member States (EU12). For Austria, Belgium, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxembourg, Netherlands, Portugal, Spain, Sweden and UK the latest date to fully comply with the Directive was 31/12/2005. For the new Member States in Central and Eastern Europe and in the Mediterranean, staged transitional periods have been set in a clear and legally binding way within the Accession Treaties; In principle these transitional periods do not exceed the year 2015; only in Romania, smaller agglomerations (with less than 10,000 p.e.) have to comply with the Directive by the end of 2018.

Specific regional assessmentNorthern Europe (Fig. 2): The connection rate is around 80 % in Norway, Sweden and Finland and, in the case of the latter two, treatment is entirely at a tertiary level. In Norway, however, about a quarter of those connected receive primary treatment only. In Iceland waste water from half of the population is not treated at all whilst the other half receives primary treatment. Trends in the rate of national population connected to the UWWTPs are affected by changes in the ratio of rural/urban population as well as by increasing use of separate individual treatment plants in rural areas.

Central Europe (Fig. 3): Central Europe has the highest overall connection rates in Europe. In Germany, Denmark, Switzerland, Austria and the Netherlands the rate of population connected to tertiary treatment range between 77-96 %. England and Wales and Scotland report connection rates to tertiary treatment are about 45%, whilst in Ireland the figure is considerably lower at 12 %., Secondary treatment in Ireland, however, increased considerably (more than tripled) between 2001 and 2005. Connection rate to tertiary treatment is relatively low in Belgium and Luxembourg 36% and 22%, respectively.

Southern Europe (Fig. 4): The overall rate of population connected to wastewater treatment ranges from 13% to 85 % in the countries of Southern Europe, being highest in Greece (85%) and Spain (81%) and lowest in Malta (13%).Tertiary treatment occurs most often in Greece and Spain with rates of 78% and 42% respectively. In other countries of the region the percentage of population connected to tertiary treatment is lower than 20%.

Eastern Europe (Fig. 5): The overall rate of population connected to wastewater treatment ranges from 50 to 75 % in countries of Eastern Europe. About 60 % of population in the Czech Republic and Estonia is connected to tertiary treatment. In Poland, Latvia and Lithuania, the rate of connection to tertiary treatment is lower, about 40%; while Hungary and Slovenia report the lowest connection rate to tertiary treatment in the Eastern Europe region 20% and 13%, respectively. For Slovakia there is no detailed information on treatment type available in Joint Questionnaire, however according to the data reported in 2007 under the Urban Wastewater Treatment Directive, 23% of total load generated in agglomerations larger than 2000 p.e.receives tertiary treatment and 63 % of total load is treated in plants equipped with secondary treatment.

South-Eastern Europe (Fig. 6).; The rate of population connected to waste water treatment plants ranges from 28 to 42 % in countries of South-Eastern Europe. Secondary or primary treatment prevails. Some tertiary treatment is applied in Turkey (10%).

Specific policy question: What is the level of the Urban Waste Water Treatment Directive (91/271/ECC) implementation in large cities of the EU Member States?

Number of EU agglomerations of more than 150 000 p.e. by treatment level, situation on 31st December 2005/2006

Specific assessment

Figure 7 summarizes the type of treatment applied in the wastewater treatment plants of 297 big cities/big dischargers (129,3 mil. p.e.) reported in 2007 by 18 Member States (AT, BE, CY, DK, EE, FI, FR, DE, HU, LV, LT, LX, NL, PT, RO, SK, SI, SE). 86 % of the total generated load produced in big cities (111,9 mil.p.e.) is discharged in sensitive areas out of which , 76 % of the total generated load receives more stringent – tertiary - treatment. Remaining load of 14% (17,4 mil p.e.) produced in big cities/big dischargers is discharged in normal or less sensitive areas. In ‘normal’ and ‘less sensitive’ areas 38 % (6,6 mil p.e.) of the generated big city load receives secondary treatment, and 46 % (7,98 mil.p.e.) receives more stringent tertiary treatment, at a standard, therefore, higher than that required by the UWWT Directive. Out of big cities reported in 2007, five had no waste water treatment at all: one in Portugal and four in Romania. Another four had only primary treatment: two in Portugal and one in France and Romania.

Justification for indicator selection

Wastewater from households and industry represents a significant pressure on the water environment because of the loads of organic matter and nutrients as well as hazardous substances. With high levels of the population in EEA member countries living in urban agglomerations, a significant fraction of wastewater is collected by sewers connected to public wastewater treatment plants. The level of treatment before discharge and the sensitivity of the receiving waters determine the scale of impacts on aquatic ecosystems.The types of treatments and conformity with the directive are seen as proxy indicators for the level of purification and the potential improvement of the water environment.

Primary (mechanical) treatment removes part of the suspended solids, while secondary (biological) treatment uses aerobic or anaerobic micro-organisms to decompose most of the organic matter and retain some of the nutrients (around 20 - 30 %). Tertiary (advanced) treatment removes the organic matter even more efficiently. It generally includes phosphorus retention and in some cases nitrogen removal. Primary treatment alone removes no ammonium whereas secondary (biological) treatment removes around 75 %.

The indicator tracks the success of policies to reduce pollution from wastewater by describing the trends in the percentage of the population connected to public wastewater treatment plants with different levels of purification.

Scientific references:

No rationale references
available

Policy context and targets

Context description

The Urban Wastewater Treatment Directive (UWWT) prescribes the level of treatment required before discharge. It requires Member States to provide all agglomerations of more than 2 000 population equivalents (p.e.) with collecting systems. Secondary treatment (i.e. biological treatment) must be provided for all agglomerations of more than 2 000 p.e. discharging into fresh waters. Special requirements with intermediate deadlines depending on the sensitivity of the receiving waters are placed on agglomerations of more than 10 000 p.e. with various size classes of agglomerations. The performance of the treatment is assessed using 5 different determinands (BOD, COD, TSS, Ntot and Ptot). In the EU Member States, there are about 25 000 agglomerations with more than 2 000 p.e., the population is 501 million inhabitants and the overall generated load of 621 million p.e.

For agglomerations smaller than described above and those equipped with a collecting system, the treatment must be appropriate, meaning that the discharge allows the receiving waters to meet the relevant quality objectives. The WFD is asking for the estimation and identification of significant point and diffuse source pollution, in particular by substances listed in Annex VIII, from urban, industrial, agricultural and other installations and activities, based, inter alia, on information gathered under Articles 15 and 17 of Directive 91/271/EEC and other Directives. From the substances listed in the Annex VIII, the following are important for the indicator : substances which have an unfavourable influence on the oxygen balance (and can be measured using parameters such as BOD, COD, etc.), materials in suspension, and substances which contribute to eutrophication (in particular, nitrates and phosphates). Member States should thus take the necessary steps to build a data collection system able to provide these data, urban source being one of the sources listed. The ultimate aim of this is to reach the target of the WFD that is a good chemical and biological status for all waters in 2015, the discharge of substances being one of the major problems to face.

Targets

The Urban Waste Water Treatment Directive (UWWTD; 91/271/EEC) aims to protect the environment from the adverse effects of urban wastewater discharges. Itprescribes the level of treatment required before dischargeand has to be fully implemented in the EU-15 countries by 2005 and in the ten new Member States by 2008 - 2015.The directive requires Member States to provide all agglomerations of more than 2 000 population equivalent (p.e.) with collecting systems and all wastewaters collected to be provided with appropriate treatment by 2005. Secondary treatment (i.e. biological treatment) must be provided for all agglomerations of more than 2 000 p.e. that discharge into fresh waters, while more advanced treatment (tertiary treatment) is required for discharges into sensitive areas. To help minimise pollution from various point sources, the Integrated Pollution Prevention and Control directive, which came into force 1996, has a set of common rules on permitting for industrial installations.

The achievements through the UWWTD and the IPPC directive have to be seen as an integrated part of objectives under the Water Framework Directive (WFD) which aim at a good chemical and biological status for all waters by 2015.

Summary report on: the identification of sensitive areas by the Member States;
the measures implemented by the Member States with the view to the deadline of 31 December 1998; wastewater treatment in major cities; verification of the identification of sensitive areas by the Commission.

Methodology

Methodology for indicator calculation

Eurostat data are used and aggregated in groups of countries. Average of percentages connected to each treatment type, weighted by total population in each country:

Formula:

National resident population = "WW0_1 National resident population" if availableor else "Table: pjan, unit: inhabitant, Population by sex and age on 1. January of each year"

% of population connected to a type of treatment for one area = sum of (National resident population X "WW0_2_1 Urban waste water treatment of primary treatment"or

"WW0_2_2 Urban waste water treatment of secondary treatment"or

"WW0_2_3 Urban waste water treatment of tertiary treatment") or

"WW0 5: Urban wastewater collecting system without treatment"

EU aggregated and national data are used as presented on DG Environment's web page and reports.

EU aggregated values representing the type of treatment applied in the wastewater treatment plants of 586 big cities/big dischargers (250,2 mil. p.e.) reported in 2011 by the Member States and Norway were retrieved from the latest version of Waterbase via a series of subsequent queries linking information on agglomerations with total generated load higher than 150 000 p.e., treatment plants serving those agglomerations and the information on the percentage of total generated load treated in particular treatment plants. First, the sequence of scripts retrieved disaggregated information at the big city/big discharger level. Disaggregated information was then aggregated at the national level.

Methodology for gap filling

For the Eurostat dataset, gap fillings were made, by using figures provided by the respective NFPs during the review process or by replacing data available in Newcronos.

Methodology references

No methodology references available.

Uncertainties

Methodology uncertainty

For the assessment shown in Figure 1, countries have been grouped to show the relative contribution on a larger statistical basis and to overcome the incomplete nature of the data. Complete dataset (ie data available for all years ad all countries) is not available for either of the geographic groups except for South-eastern countries (since the beginning of 2000 ies). Aggregated values are calculated only for the years for which the most complete dataset (with regard to number of responding countries) is available.

Data sets uncertainty

Rationale uncertainty

Data gained from the UWWTD focuses on the performance of the treatment plant alone. But wastewater treatment systems could also include sewer networks with storm water overflows and storages which are complex and whose overall performance is difficult to assess. In addition to the treatments covered by the UWWTD there are other possible treatments, mostly industrial, but also independent treatments of smaller settlements outside urban agglomerations not included in UWWTD reporting. Compliance with the levels defined in the directive therefore does not guarantee that there is no pollution due to urban wastewater.

In addition Urban Waste Water Treatment is the main waste water treatment used across the EEA area, but there are other possible treatments that are treatment in Other Waste Water Treatment, mostly industrial, or in independent treatments. Furthermore there are differences in how countries have interpreted and implemented the Directive leading to differences in the data reported. There are especially variations in the definitions of different classes of treatment between countries (classes based on performance or on design capacity and tertiary treatment for N, P or organic matter) that in turn lead to differences in the level of purification attributed by the countries to the classes. These differences all the more emphasize the problem of using types of treatment plant as a proxy for the level of purification. Member States have also been taken to court by the European Commission because of insufficient application of the Directive.